RENEW OR SUBSCRIBE TO PPM
Subscription is FREE for qualified healthcare professionals in the US.
14 Articles in Volume 18, Issue #9
Assessing Arthralgia in Children
Children, Opioids, and Pain: The Stats & Clinical Guidelines
How to Fit into a New Practice
How to Talk to Your Chronic Pain Patients
How to Treat Opioid Use Disorder in Pregnant Women
Intranasal Ketamine for Acute Pain in Children
Medication Selection for Comorbid Pain Management (Part 3)
MR Neurography: Using Peripheral Nerve Imaging as a Pain Diagnostic
Naloxone in Schools; Buprenorphine Conversions; OUD Management
Opioid Conversion Calculations and Changes
Pes Anserine Tendino-Bursitis as Primary Cause of Knee Pain in Overweight Women
Self-Management of Chronic Pain in Primary Care
The Homebound Adolescent: Managing Chronic Pain Conditions in the Pediatric Population
The Opioid Band-Aid: The State of Pain Pills, Congressional Bills, and Healthcare in the US

Pes Anserine Tendino-Bursitis as Primary Cause of Knee Pain in Overweight Women

A retrospective study of pes anserine corticosteroid injections in treating chronic knee pain in women with and without osteoarthritis.
Pages 37-42 ; 50

Obese individuals are at increased risk of developing knee osteoarthritis.1,2 A “vicious cycle” has been described in which joint pain leads to decreased physical activity; the subsequent weight gain produces increased joint surface forces, thus accelerating the development of osteoarthritis (OA) and disabling knee pain.3 Women, especially those of ethnic minority groups, have been found to be disproportionately affected by this pattern.3

Decreasing the knee pain to tolerable levels may allow an individual to live a more active life, and perhaps break the cycle. Whereas knee arthroscopy has been the mainstay of treatment for those with less advanced disease, multiple studies have shown that partial meniscectomy is generally ineffective in patients with degenerative knees,4-6 especially in overweight individuals.7 Obese individuals are also prone to develop comorbidities, such as diabetes and heart disease, and thus present an increased risk with invasive procedures such as total knee replacement.8 Because the problem of knee pain in overweight women with OA has proven difficult to treat, perhaps understanding the possible pathogenesis of knee pain in this patient population would be clinically beneficial.

In 1937, Eli Moshkowitz, MD, described a painful knee condition in overweight women who were tender in the pes anserine region and not on the joint line.9 The pes anserinus (“goose foot”) consists of the tendinous attachments of the semitendinosus, gracilis, and sartorius muscles. A bursa exists underneath these tendons, and its location has been well-described in an anatomical study.10 The term “pes anserine tendino-bursitis,” or PATB, is now used to describe this condition. A few studies have shown that PATB may contribute to knee pain in patients with OA.11,12 Injection of the pes bursa with corticosteroid has shown to be an effective treatment, including in patients with OA.13,14

A retrospective study of pes anserine corticosteroid injections in treating chronic knee pain in women with and without osteoarthritis. (Source: 123RF)

There have been few studies, however, that have looked at the prevalence of PATB. One investigation using MRI identified pes bursitis in 2.5% of patients with knee pain.15 Two studies in which ultrasound was utilized on patients with painful knee OA found an incidence of pes anserine bursitis in 8 and 20%, respectively.16,17 There are no published reports on the prevalence of PATB specifically in overweight women. An association between obesity and PATB has not been proven, and one study even showed that obesity was actually not a risk factor.12

The goals of this case report are to identify the frequency of PATB in overweight mature women who present with severe knee pain, and to determine the effectiveness of treatment with a steroid injection into the pes anserine region. If reducing the pain in the pes anserinus significantly decreases the patient’s symptoms, even in the presence of osteoarthritis, this result would suggest that PATB is a significant contributor, if not the main source, of their pain.

Methods & Patient Base

The Clinica de Salud del Valle de Salinas Institutional Review Board, in Salinas, California, made a determination of “EXEMPT” with respect to Human Subject Research requirements. This paper therefore offers a retrospective review of medical records of overweight women with knee pain treated between January 1, 2015 and January 1, 2017 in an outpatient clinic setting using a treatment approach based solely on history and physical examination, specifically focusing on the area of maximum tenderness.

During this time period, 196 consecutive overweight (BMI 25 or over) women age 40 and older, involving 260 knees, presented with a chief complaint of knee pain lasting at least two months and not associated with significant recent trauma (eg, fracture or cruciate ligament tear). All patients had a pain assessment using a Visual Analog Pain Score (VAS) and were given a pain score ranging from 0 to 10.

Patients included in the study (115 patients/148 knees) had “severe knee pain” (6 or higher VAS), and had received some form of conservative management (eg, NSAIDS or other pain medication, physical therapy, and/or exercises) with at least four weeks follow-up. Patients included in the review had a functional range of motion (5 to 90 degrees at minimum).

Six patients with far advanced OA with limited knee range of motion and/or severe deformity (ie, greater than five degrees varus and 15 degrees of clinical valgus) were excluded. Also excluded were 51 patients with mild/moderate pain who improved with conservative treatment and 27 patients for whom there was no follow-up after the first visit (six in this group had received an injection.)

Assessment & Treatment

In addition to a history and pain assessment, a complete knee examination was performed in the supine position. In addition, leg strength was assessed by ability to perform straight leg raises against resistance.

For the study examination, the patients were placed in a sitting position with the knee flexed over the edge of the table to 90 degrees. Palpation was performed, which included the femoral condyles, joint lines, patella area, and patellar tendon (labeled #1-6 in Figure 1a). To help find the location of maximum tenderness in the pes region, a horizontal line was drawn in the proximal medial tibia between the tibial tubercle anteriorly and the apex of the knee flexion crease posteriorly (see Figure 1a).

For each patient, the location of maximum tenderness was identified and recorded. The area of maximal tenderness in the pes anserine area was consistently found approximately one centimeter posterior to the center of this line (see “X” #7 in Figure 1a). If the maximum tenderness was identified in the pes area (“#7”), the patient was diagnosed with pes anserine tendino-bursitis, and offered an injection into that specific location. Those with tenderness elsewhere were treated according to the diagnosis.

Patients opting for the injection signed the consent for the procedure explaining the risks and benefits. After sterile preparation, the injection was done using a one-and-a-half-inch long 22-gauge needle with an entry angle of approximately 45 degrees to the coronal plane of the tibia angling from anteromedial to posterolateral. A longer needle is not used to avoid any possibility of trauma to the neurovascular structures posteriorly (see Figure 1b). Lidocaine (5 cc of 1%) in one syringe is injected into the subcutaneous and deeper layers all the way to bone, and then, without removing the needle, steroid (80 milligrams of kenalog) from a second syringe is injected around the bone (see Figure 1c). It should be noted that in all cases the one and a half inch long needle was sufficient to reach the bone, and occasionally required “puckering” of the tissues (see Figure 1c).

Figure 1, left to right: a) Locating maximum tenderness in the pes region; b) use of a one-and-a-half-inch 22-guage needle with an entry angle of approximately 45 degrees to the coronal plane of the tibia; and c) injection of steroid by second syringe around the bone. (Images courtesy of the author.)

All patients were then given a thigh strengthening program demonstrated to them by the treating orthopedic surgeon. Patients were encouraged to perform sitting and supine straight leg raises (with the knee held in full extension) as well as hip abductor strengthening as often as possible (eg, when watching television). At each visit, patients were reminded to do the self-supervised strengthening exercises.

Patient Education & Follow-Up

After the injection, the patients were also required to demonstrate their understanding of the thigh-strengthening exercises and then ambulated in the hallway. Their post-injection pain was assessed 10 to 15 minutes after the injection using a VAS diagram.

All patients included in the study had plain film knee radiographs that included an AP and lateral view. The x-ray as well as the x-ray report was reviewed by the treating orthopedist, who assigned a rating based on the degree of degenerative changes using the Kellgren-Lawrence (“K-L”) classification system (grades 0-4). Those with no or minimal OA were combined as K-L grade “0-1,” and K-L grades 2-4 were rated separately as per the K-L classification criteria.

Patients were seen back 1 month after the injection. Those who had recurrence of symptoms within four weeks (VAS 6 or greater) were considered to have “failed” the injection, and other causes of pain were considered. Repeat injections are generally given with at least a 3- to 4-month interval between injections.

Results

In all, 115 consecutive women (involving 148 knees) met the selection criteria and had persistent, “severe” pain complaints, despite conservative treatment (eg, NSAIDs, PT, exercises), with an average VAS of 7.9 (ranging from 6 to 10). The average age was 62.7 (ranging from 39 to 88), and the average BMI was 34.9 (ranging from 25 to 59). The average duration of symptoms was 16.1 months (ranging from 2 months to 24 months) and average length of follow-up was 5.0 months (ranging from 1 month to 16 months).

Kellgren-Lawrence Grades and Osteoarthritis Presence

Of the 148 knees, ratings were as follows:

  • 27 (18.2%) - K-L grade 0-1
  • 32 (21.6%) - K-L grade 2
  • 59 (39.9%) - K-L grade 3
  • 30 (20.3%) - K-L grade 4.

Thus, 81.8% of the knees had OA with varying degrees of radiographic joint space narrowing (see also Figure 2). In regard to the location of arthritis, 67 knees (45.2%) had predominantly medial compartment involvement, 17 knees (11.4%) had predominantly lateral compartment involvement, and 64 knees (43.2%) had multicompartmental OA.

Figure 2. Osteoarthrits prevalence, graded by Kellgren-Lawrence (K-L) classification system. (Source: Author provided)

In terms of maximal tenderness, 141 of 148 knees (95.3%) had maximal tenderness at the pes bursa and received a pes anserine injection. Of the five patients (7 knees) who did not demonstrate maximal tenderness at the pes anserine, two had symptomatic meniscal tears and were treated with arthroscopy. Two patients (3 knees) were managed with intra-articular injections, and one patient (2 knees) was referred for total knee replacement.

Injection Relief and Effects

Of the 110 patients/141 knees who received a pes bursa injection, the average VAS score preinjection was 7.9 (see Figure 3). In addition, 95.0% (134/141 knees) had significant pain relief after the injection (VAS 4 or less) with an average VAS score of 1.2 (P < 0.00001) (see Figure 4).

Figure 3. Average VAS score before injection, using Kellgren-Lawrence (K-L) classification. (Source: Author provided)

Figure 4. Average VAS score immediately after injection, using Kellgren-Lawrence (K-L) classification. (Source: Author provided)

At 1 month, follow-up was obtained on 104 patients/135 knees who were injected into the pes bursa, of which 119 of 135 knees (88.1%) had maintained significant pain reduction (VAS 4 or less), with an average VAS score of 2.4 (P < 0.00001) (see Figure 5).

Figure 5: Average VAS score 1 month after injection, using Kellgren-Lawrence (K-L) classification. (Source: Author provided)

Of the 119 knees that responded to the injection, there was a recurrence of severe pain (VAS 6 or greater) in 36 knees, an overall recurrence rate of 30.3%, with a rates of 8.7% in patients with no or minimal OA (K-L grades 0/1) versus 35.4% in patients with OA with some degree of joint space narrowing (K-L grades 2-4) (P < 0.0025) (see Figure 6).

Figure 6. Recurrence rate of pain, using Kellgren-Lawrence (K-L) classification. (Source: Author provided)

All patients with initial pain relief (of at least four weeks) with a subsequent recurrence requested a reinjection, and follow-up of at least four weeks was obtained on 23 patients (34 knees). The average VAS score prior to reinjection was 7.3, and 73.5% maintained significant pain relief for a minimum of one month with an average VAS score of 2.8 (P < 0.00001). The success rate (patients who wanted to continue with pes injections) for those who received at least one reinjection was 23/34 knees, or 67.6%.

Overall Follow-Up

In summary, of the original 104 patents/135 knees treated for PATB with at least 1 month follow-up, a total of 22 knees, 16.3%, ultimately did not respond to the pes anserine injections (see Figure 7). In regards to the 16 patients (22 knees) who did not respond to pes injections, 2 patients (2 knees) were treated with arthroscopy for meniscal tears and 6 patients (9 knees) were referred for knee replacements.

Figure 7. Failure rate of corticosteroid treatment, using Kellgren-Lawrence (K-L) classification. (Source: Author provided)

As to complications, there were no infections. One patient, a diabetic, claimed to have experienced a transient elevation in blood sugar glucose after the injection.

Discussion

The goals of this retrospective clinical review were to:

  • assess the source of knee pain in the specific demographic of overweight, middle-aged and elderly women (average age 63 with BMI 35); and
  • determine if treating the presumed source of the pain, pes anserine tendino-bursitis (PATB), with a steroid injection could decrease the pain.

As presented, physical examination identified the area of maximal tenderness, which helped to establish the diagnosis, irrespective of radiologic findings. The primary source of the knee pain as determined by the area of maximum tenderness in approximately 95% of the patients included in the study was the pes anserine area, and this was independent of the degree of OA. A steroid injection placed into the area of maximum tenderness provided significant pain relief in almost 90% of patients after 1 month, also independent of the degree of OA. While the recurrence rate was around 30%, approximately 70% of patients with recurrent pain were successfully treated with one or more re-injections.

Of the original 104 patients/134 knees treated with a pes anserine injection, more than 80% with OA, only 16% ultimately did not respond to the treatment regimen, and were referred for other interventions.

The results point to the conclusion that, in this specific demographic of mature overweight women, pes anserine tendino-bursitis appears to be a significant and previously unappreciated source of disabling chronic knee pain, including in those patients with osteoarthritis. If the pain in the pes anserine area can be significantly reduced with a steroid injection, the patient is likely to experience significant relief.

Related Research

An important part of the treatment of these overweight women is thigh muscle strengthening. While no formal testing was done, the patients included herein universally seemed to have quadriceps and hip abductor weakness. The importance of these exercises aligns with research that has shown quadriceps strengthening is associated with a reduction of knee pain caused by OA.18

This study used physical examination, and not ultrasound, to guide the placement of the steroid injection. The target of the injection was the bone and periosteum, as opposed to the bursa. In the author’s experience, the area of maximum tenderness in PATB is almost always found in the same location: slightly posterior to the middle of a line drawn between the apex of the knee flexion crease and the tibial tubercle (see Figure 1a). This site appears to correspond to where the gracilis and sartorius tendons con-verge as they begin their attachment to the tibia, as seen in the anatomical study by He-Jun, et al.6 While identifying the area of maximum tenderness on physical examination may be challenging, especially in morbidly obese patients, by locating the landmarks of the tibial tubercle and the knee flexion crease, one can consistently diagnose PATB with palpation.

Another study using only physical examination identified 48% of patients with knee OA as having PATB, although this study was not limited to overweight women.9 By comparison, two studies that relied on ultrasound diagnosed pes anserine bursitis in only 8% and 20%, respectively, in patients with knee OA.12,13

The recurrence rate was significantly higher in those patients with at least some degree of OA (32%) versus those with no or minimal OA (8%) (P < .0025). This suggests that knee OA may predispose an individual to PATB; this could be due to mechanical malalignment or perhaps secondary to quadriceps inhibition and subsequent thigh muscle weakness, factors that may ultimately increase the stress on the pes anserine tendons.

The etiology of PATB in patients with or without OA has yet to be elucidated. As noted, Moshkowitz proposed in 1937 that a bursitis may result from “strain in the use of the sartorius and gracilis muscles, which act to lift the body in stepping upward and downward,” and this bursitis then causes an “osteoplastic periostitis of the adjacent area of the inner tibia.”9 This proposed pathophysiology would help explain why the area of maximum tenderness is consistently found in the same location, presumably at the confluence of the sartorius and gracilis tendons, and why injecting the periosteum in this specific location consistently provides substantial pain relief. Fluid return suggestive of a bursal injection is only occasionally encountered, thus suggesting that PATB may ultimately be more of a periostitis than a bursitis.

The findings in this study suggest that diagnosing and treating PATB may offer an alternative conservative approach for patients suffering from osteoarthritis who currently have limited options. Neither oral glucosamine or intra-articular injections with hyaluronic acid are recommended for the treatment of knee OA by the American Academy of Orthopedic Surgeons evidenced-based guidelines.19 The results with steroid injections have been mixed and, thus, no evidenced-based recommendation have been provided.19 Moreover, arthroscopy and partial meniscectomy in middle-aged and older patients with degenerative changes in the knee have been found to be of questionable efficacy, and the risks, including the possible acceleration of osteoarthritis, may outweigh the benefits.6,20,21 Knee replacement then becomes the treatment of last resort, and this procedure can be risky in the setting of obesity and comorbidities.8

Recommendations

The approach used in this review has the potential to significantly reduce testing and unnecessary surgical procedures, as well as cost. MRI is only considered in patients without significant knee OA and with a history as well as physical examination suspicious for a meniscal tear. If an injection into the PATB can provide lasting pain relief, then there is less justification for surgery, whether it be an arthroscopy or total knee replacement. The PATB injection can be done in an outpatient clinic setting, and neither ultrasound nor fluoroscopy is needed; thus, the approach is cost-effective.

It should be noted that there are a number of weaknesses in this study. Follow-up was only short term (5 months on average). Thus, no conclusions can be drawn as to long-term outcome in these patients. There was only one provider doing the treatment and the evaluation, and, thus, there is observer bias. This is a retrospective report of one approach, and there is no control group. The study measured pain levels, but not function. While quadriceps strength was assessed, this was done through manual testing by the treating orthopedist. There was no formal testing in regard to assessing muscle strength.

In regard to the x-rays, only some were weight bearing, thus not accurately assessing alignment and perhaps not identifying some cases of OA and underestimating the degree of OA in others. However, it needs to be emphasized that the approach used in this study is not based on radiological findings.

Future studies on PATB could include the following: comparing the effectiveness of PATB injections with conventional intra-articular steroid injections in patients with knee osteoarthritis, evaluating the effect of age, weight, and gender on the location of knee pain in patients with osteoarthritis, and elucidating the pathogenesis of PATB.

In conclusion, this study suggests that pes anserine tendino-bursitis may be a significant source of severe knee pain in overweight middle-aged and elderly women, including those with knee OA. Keeping with the theme of exhausting conservative treatment options prior to surgery, this study suggests that PATB needs to be considered before proceeding to more invasive options that carry additional risk and cost. A well-placed pes anserine corticosteroid injection along with thigh muscle strengthening provides a safe and economical alternative for the treatment of debilitating knee pain in mature overweight women, including those with osteoarthritis.

Last updated on: January 16, 2019
Continue Reading:
Successful Nonoperative Treatment of Persistently Painful Knees Following Total Knee Arthroplasty—A Case Series
close X
SHOW MAIN MENU
SHOW SUB MENU